node.js request stuck in middleware function (authentication)? - node.js

Question

I am building a node.js server to handle logins and actions in my iOS app. One of the functions I wrote is checkAuth, which is middleware for most of my requests to check if a user is authenticated and has permission to do what he wants to do.
Now I am facing a problem where sometimes, but not always, the middleware function (checkAuth) is stuck. I receive logs from this function in my console, but nothing from the request (which should happen after authentication is successful).
This is the function I currently wrote. It is not optimized yet as I am testing everything, but it should do what I want it to do (and it does, most of the time):
const saltRounds = process.env.JWT_ROUNDS
const secret = process.env.JWT_SECRET
const checkRefreshTime = 10 // set to 10 seconds for testing, will increase later
function checkAuth(req, res, next) {
var token = req.headers['x-access-token']
jwt.verify(token, secret, (error, decoded) => {
console.log("checking auth")
if(error) {
console.log(error)
res.json({ errorCode: 406 })
} else {
const decoded = jwt.verify(token, secret)
var checkTime = (Date.now() / 1000) - checkRefreshTime;
if (decoded.iat < checkTime) {
console.log("DEC:", decoded)
const userID = decoded.userID
const queryString = "SELECT userRefreshToken, userName, userDisplayName, userProfilePicURL, userDOB, userGender FROM users WHERE userID = ? LIMIT 1"
pool.getConnection(function(error, connection) {
if(error) {
console.log(error)
res.json({ errorCode: 500 })
}
connection.query(queryString, [userID], (error, selectRows, fields) => {
if(error) {
console.log(error)
res.json({ errorCode: 500 })
}
if(selectRows.length > 0) {
if(selectRows[0].userRefreshToken == decoded.userRefreshToken) {
var userAge = moment().diff(selectRows[0].userDOB, 'years');
const payload = {
userID: userID,
userName: selectRows[0].userName,
userDisplayName: selectRows[0].userDisplayName,
userProfilePicURL: selectRows[0].userProfilePicURL,
userRefreshToken: selectRows[0].userRefreshToken,
userAge: userAge,
userGender: selectRows[0].userGender
}
var newToken = jwt.sign(payload, secret, { expiresIn: '21d' });
console.log("new token sent ", newToken)
res.locals.authToken = newToken
console.log("moving to next")
return next()
} else {
console.log("wrong refresh token")
res.json({ errorCode: 405, authResult: false })
}
} else {
console.log("0 results found!")
res.json({ errorCode: 503, authResult: false })
}
connection.release()
})
})
} else {
console.log("moving to next 2")
return next()
}
}
})
}
It probably isn't the most beautiful code you have ever seen. That's not my issue at this moment - I will optimize at a later time. Right now I am concerned about the fact that sometimes the function is stuck after the second check. The last output I then receive is "DEC: " followed by the decoded token in my console (line 16).
Other useful information: I run my server on an Ubuntu 18.04 server from DigitalOcean and use forever to keep it running:
forever start --minUptime 1000 --spinSleepTime 1000 server.js
Anybody who knows why this is happening?
EDIT: as per comment, the definition of pool
var pool = mysql.createPool({
connectionLimit: 100,
host: process.env.DB_HOST,
user: process.env.DB_USER,
password: process.env.DB_PASS,
database: process.env.DB_BASE,
ssl : {
ca : fs.readFileSync('***********'),
key : fs.readFileSync('*********'),
cert : fs.readFileSync('********'),
},
charset : 'utf8mb4',
dateStrings: true
})

Answer 1

I don't see where pool is defined anywhere. That could be throwing an error in the server logs.
Put a console log in the connection function to check that it actually connected to mySQL since that is the next function in the chain.